The present invention relates to a character and/or figure displaying apparatus for receiving character/figure information signals to decode the received signals and for displaying the character/figure information on a display section.
As one of the various multiplex television broadcasting systems recently devised to efficiently utilize the television broadcasting waves, a multiplex television character broadcasting system has been put to practice in which character/figure information signals of news, weather forecast, stock market quotations, etc. consisting of characters and figures can be displayed on television receivers in households.
In addition to this, videotex systems such as CAPTAIN have also been put to use in which character/figure information signals are transmitted through the telephone lines and displayed on television sets.
Referring next to the drawings, a description will be given of a character and/or figure information displaying or display apparatus capable of receiving the character/figure information signals discussed above to display the information on a screen of a television set.
FIG. 1 is a block diagram showing the configuration of a conventional character/figure information display apparatus. This system comprises a character/figure information decoder section 1 for decoding the character/figure information signals into character/figure image signals associated with the characters and figures, a microprocessor circuit 2 for controlling the character/figure information decoder section 1, a receiver circuit 3 for detecting the character/figure information signals in a form of the digital data signals from the composite video signals, a random access memory (RAM) 4 as an area for storing therein the received character/figure information signals and as a work area of the microprocessor circuit 2, a read-only memory (ROM) 5 for storing therein programs to control the microprocessor circuit 2, a display memory 7 for storing therein the character/figure image signals decoded by the microprocessor circuit 2, a display processing circuit 6 for processing the character/figure image signals stored in the display memory 7 to compose RGB signals, a character/figure generator 9 disposed to decode the character figure information signals into the image signals, a supplemental sound decoder 8 for processing supplemental sound data signals included in the character/figure information signals, and a key pad 10 for supplying the character/figure information decoder section 1 with instructions such as a selection for the character/figure information signals. The configuration of FIG. 1 further includes a television signal receiver section 20, an antenna 21, a television signal receiver circuit 22, an audio demodulator/amplifier circuit 23, and a luminance amplifier/color demodulator circuit 24 for detecting the video signals from the composite video signals. Moreover, the apparatus comprises a video/audio switch circuit 25 for achieving a change over between a combination of the video and audio signals produced from the television signals receiver circuit 22 and a combination of the RGB signals and the supplemental sound signal produced from the character/figure information decoder section 1, an audio amplifier output circuit 26, a speaker 28, a video amplifier output circuit 27, and a display section 29 for displaying thereon a visual image.
Next, a description will be given of the operation of the character/figure information display apparatus configured as above.
An RF television signal received by the antenna 21 is decoded by the television signal receiver circuit 22 of the television signal receiver section 20, thereby acquiring a composite video signal and an audio signal. The composite video signal is sent to the receiver circuit 3 of the character/figure information decoder section 1 so as to obtain a character/figure information signal therefrom. By use of the key pad 10, the user can supply the microprocessor circuit 2 with an indication to select desired items from the various character/figure information items. The microprocessor circuit 2 then selects a character/figure information signal associated with the information specified from the key pad 10 to store the signal in the RAM 4. Furthermore, the microprocessor circuit 2 decodes the character/figure information signal according to contents of the programs stored in the ROM 5 by appropriately using the character generator 9 when necessary. The character/figure image signal thus decoded from the character/figure information signal is loaded in the display memory 7. The signal stored in the display memory 7 is acquired by the display processing circuit 6, which produces therefrom the RGB signals. The supplemental sound data included in the character/figure information signal is transformed into a supplemental sound signal by the supplemental sound decoder 8.
The audio signal and the composite video signal demodulated by the television receiver circuit 22 are respectively fed to the audio demodulator/amplifier circuit 23 and the luminance amplifier/color demodulator circuit 24. Resultant signals are delivered to the video/audio switch circuit 25. When displaying a character/figure image, the switching circuit 25 selects a combination of the RGB signals and the supplemental second signal from the decodes section 1, while displaying a television image, a combination of the video and audio signals from the television receiver circuit 22 is selected. The selected signals are respectively passed via the audio amplifier output circuit 26 and the video amplifier output circuit 27 to the speaker 28 and the display section 29, respectively. Through the operations above, the character/figure information selected by the user can be displayed on the display section 29.
However, in the character/figure information display apparatus, the image which can be displayed on the display section is limited to character/figure information having a display density equivalent to a scan period of the television signal (associated with level A in the multiplex television character broadcasting and with ranks 1, 2, and 4 in the CAPTAIN system). In a case where character/figure information having a higher display density (associated with level B in the multiplex television character broadcasting and with ranks 3 and 5 in the CAPTAIN system) is to be displayed, the display capability is required to be increased in the display section including the display equipment such as a cathode ray tube (CRT) and hence the system cost is considerably increased.